Eugenol-containing essential oils loaded onto Chitosan/Polyvinyl alcohol blended films and their ability to eradicate Staphylococcus aureus or Pseudomonas aeruginosa from infected microenvironments
Chronic wounds (CW) create numerous entryways for pathogen invasion and prosperity, further damaging host tissue and hindering its remodeling and repair. Essential oils (EOs) exert quick and efficient antimicrobial (AM) action, unlikely to induce bacterial resistance. Cinnamon leaf and clove oils (CLO and CO) display strong AM activity, namely against Staphylococcus aureus and Pseudomonas aeruginosa. Chitosan (CS) is a natural and biodegradable cationic polysaccharide, also widely known for its AM features. CS and poly (vinyl alcohol) (PVA) films were prepared (ratio 30/70 w/w; 9 wt%) by the solvent casting and phase inversion method. The film's thermal stability and chemical composition data reinforced polymer blending and EO entrapment. Films were supplemented with 1 and 10 wt% of EO in relation to total polymeric mass. The film thickness and degree of swelling (DS) tended to increase with EO content, particularly with 10 wt % CLO (* p < 0.05). UV-visible absorbance scans in the 250-320 cm-1 region confirmed the successful uptake of CLO and CO into CS/PVA films, particularly with films loaded with 10 wt% EO that contained 5.30/5.32 times more CLO/CO than films supplemented with 1 wt% EO. AM testing revealed that CS films alone were effective against both bacteria and capable of eradicating all P. aeruginosa within the hour (*** p < 0.001). Still, loaded CS/PVA films showed significantly improved AM traits in relation to unloaded films within 2 h of contact. This study is a first proof of concept that CLO and CO can be dispersed into CS/PVA films and show bactericidal effects, particularly against S. aureus, this way paving the way for efficient CW therapeutics.Portuguese Foundation for Science and Technol-ogy (FCT), FEDER funds by means of Portugal 2020 Competitive Factors Operational Program(POCI), and the Portuguese Government (OE) for funding the project PEPTEX with reference PTDC/CTM-TEX/28074/2017 (POCI-01-0145-FEDER-028074). The authors also acknowledge project UID/CTM/00264/2021 of the Centre for Textile Science and Technology (2C2T), funded by nationalfunds through FCT/MCTES. The authors also thankÂngela Silva for performing STA and DSCmeasurements and assisting with enthalpy calculations and FTIR set-up, Eng. Joaquim Jorge Peixotofor showing us how to use the film thickness meter, as well as to Eng. Paulo Madureira from IsazaScientific for clarifications regarding the employed UV-visible spectroscopy metho
